Fuel pump

ABSTRACT

The present invention, in one form, is a fuel pump having increased pump inlet suction and outlet pressures as compared to known fuel pumps. Such pressure increases enable use of one fuel pump even with an engine including multiple cylinder banks, and facilitates elimination of vapor and air bubbles in the fuel. The fuel pump also does not include small, or narrow passages that are prone to be clogged by dirt or the like. More specifically, and in one embodiment, the fuel pump includes a pump housing including an inlet and an outlet. An inlet nozzle extends from the inlet, and -an outlet nozzle extends from the outlet. The inlet nozzle is configured to be coupled to a fuel line extending from a fuel tank, and the outlet nozzle is configured to be coupled to a fuel line extending to the engine block. The pump further includes first and second pump inlet covers. Each cover includes an air nozzle. The air nozzles are configured to be coupled to air lines extending from select cylinders of the engine as described below in more detail. The covers and the housing form first and second pumping chambers. The pump also includes a first check valve located within the inlet nozzle and a second check valve located within the outlet nozzle. A first diaphragm and a first spring are located in the first pumping chamber, and a second diaphragm and a second spring are located in the second pumping chamber. The first pumping chamber is in flow communication with a passage through the inlet nozzle, and the second pumping chamber is inflow communication with a passage through the outlet nozzle. The first pumping chamber is in flow communication with the second pumping chamber via a check valve.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of U.S. patent application Ser. No. 10/211,556, which was filed on Aug. 5, 2002, which is a continuation of U.S. patent application Ser. No. 09/344,029, now abandoned, which was filed on Jun. 25, 1999. The contents of both applications are incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] This invention relates generally to fuel pumps, and more specifically, to fuel pumps for marine engines.

[0003] Internal combustion engines typically include a fuel pump for pumping fuel from a fuel tank to combustion chambers of the engine cylinders. In some known outboard engines including two cylinder banks, e.g., a V-6 type outboard engine, two fuel pumps may be required to pump fuel to each cylinder bank. Specifically, a first fuel pump delivers fuel to a first cylinder bank, and a second fuel pump delivers fuel to a second cylinder bank. Separate fuel pumps are required for each cylinder bank because such known fuel pumps only deliver fuel sufficient for one cylinder bank.

[0004] In addition, and to ensure efficient operation of an internal combustion engine, liquid fuel with no vapor bubbles should be delivered to the engine combustion chambers. Vapor can be created if the liquid fuel is allowed to expand within, or at the outlet of, the fuel pump. Vapor bubbles can form in the fuel at the inlet of the pump due to the fuel being drawn from the tank.

[0005] Also, at least some known fuel pumps includes small passages through which the fuel must flow. Such passages, however, can be clogged by dirt particles or other particles that may be carried by the fuel. As a result, an insufficient amount of fuel, or possibly even no fuel, may flow through the pump to the engine combustion chambers.

[0006] Further, some known fuel pumps are bulky and expensive to fabricate. With outboard engines, space within the engine is limited. These known fuel pumps therefore not only acid costs to the engine, but also occupy space that could be used for other components.

BRIEF SUMMARY OF THE INVENTION

[0007] The present invention, in one aspect, is a fuel pump having increased pump inlet suction and outlet pressures as compared to known fuel pumps. Such pressure increases enable use of one fuel pump even with an engine including multiple cylinder banks, and facilitates elimination of vapor and air bubbles in the fuel. The fuel pump also does not include small, or narrow passages that are prone to be clogged by dirt or the like.

[0008] More specifically, and in one embodiment, the fuel pump includes a pump housing including an inlet and an outlet. An inlet nozzle extends from the inlet, and an outlet nozzle extends from the outlet. The inlet nozzle is configured to be coupled to a fuel line extending from a fuel tank, and the outlet nozzle is configured to be coupled to a fuel line extending to the engine block. The pump further includes first and second pump inlet covers. Each cover includes an air nozzle. The air nozzles are configured to be coupled to air lines extending from select cylinders of the engine as described below in more detail. The covers and the housing form first and second pumping chambers.

[0009] The pump also includes a first check valve located within the inlet nozzle and a second check valve located within the outlet nozzle. A first diaphragm and a first spring are located in the first pumping chamber, and a second diaphragm and a second spring are located in the second pumping chamber. The first pumping chamber is in flow communication with a passage through the inlet nozzle, and the second pumping chamber is in flow communication with a passage through the outlet nozzle. The first pumping chamber is inflow communication with the second pumping chamber via a check valve.

[0010] Prior to operation, air lines are coupled to the air nozzles. Typically, the air lines extend from engine cylinders that operate 180 degrees out-of-phase so that alternating pressure and vacuum forces are applied to the respective diaphragms. In addition, a fuel line from a fuel tank is coupled to fuel inlet nozzle, and a fuel line to the cylinders is coupled to fuel outlet nozzle.

[0011] In operation, the engine cylinders generate positive and negative pressure pulses. For example, and in an engine with an even number of cylinders, when one cylinder is on an upstroke, there is at least one cylinder on a downstroke at the same time. Therefore, one cylinder pulse is positive and one cylinder pulse in negative. When the negative and positive pulses are exerted on opposite sides of a diaphragm, the pulses are additive. In the above described fuel pump, when a positive pulse is present at one nozzle, a negative pulse is present at the other nozzle. Generally, fuel passes through the valve between and from the first pumping chamber to second pumping chamber. When the pulses are reversed, fuel is forced through the outlet passage and drawn into the inlet passage.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is a perspective view of a fuel pump in accordance with one embodiment of the present invention.

[0013]FIG. 2 is an exploded view of the pump shown in FIG. 1.

[0014]FIG. 3 is a cross-sectional view through the pump along line 3-3 shown in FIG. 1.

[0015]FIG. 4 is a side view of the pump housing.

[0016]FIG. 5 is a top view of the pump housing shown in FIG. 4.

[0017]FIG. 6 is a bottom view of the pump housing shown in FIG. 4.

[0018]FIG. 7 is an end view of a first end of the pump housing shown in FIG. 4.

[0019]FIG. 8 is am end view of a second end of the pump housing shown in FIG. 4.

[0020]FIG. 9 is a side view of a pump inlet cover.

[0021]FIG. 10 is a top view of the pump inlet cover shown in FIG. 9.

[0022]FIG. 11 is a bottom view of the pump inlet cover shown in FIG. 9.

[0023]FIG. 12 is an end view of a first end of the pump inlet cover shown in FIG. 9.

[0024]FIG. 13 is an end view of a second end of the pump inlet cover shown in FIG. 9.

[0025]FIG. 14 is a side view of a pump port.

[0026]FIG. 15 is an end view of a first end of the pump port.

[0027]FIG. 16 is an end view of a second end of the pump port.

[0028]FIG. 17 is a top view of a pump in accordance with a second embodiment of the present invention.

[0029]FIG. 18 is a cross sectional view of the pump along line 18-18 shown in FIG. 17.

DETAILED DESCRIPTION OF THE INVENTION

[0030]FIG. 1 is a perspective view of a fuel pump 100 in accordance with one embodiment of the present invention. Fuel pump 100 includes a pump housing 102 including an inlet 104 and an outlet 106. An inlet nozzle 108 extends from inlet 104, and an outlet nozzle 110 extends from outlet 106. Inlet nozzle 108 is configured to be coupled to a fuel line extending from a fuel tank, and outlet nozzle 110 is configured to be coupled to a fuel line extending to the engine block. Pump 100 further includes first and second pump inlet covers 112 and 114. Each cover 112 and 114 includes an :air nozzle 116 and 118. Air nozzles 116 and 118 are configured to be coupled to air lines extending from select cylinders of the engine as described below in more detail. Housing 102 also includes flanges 120 having respective openings 122 therethrough to facilitate securing pump 100 to an engine.

[0031]FIG. 2 is an exploded view of pump 100 shown in FIG. 1. As shown in FIG. 2, pump 100 includes a first check valve 124 configured to be located within inlet nozzle 108 and a second check valve 126 configured to be located within outlet nozzle 110. When assembled to housing 102, first check valve 124 is located in inlet 104, and second check valve 126 is located in outlet 106. Pump 100 also includes a first diaphragm 128 and a first spring 130 configured to be located in a first pumping chamber 132, and a second diaphragm 134 and a second spring 136 configured to be located in a second pumping chamber 138. Covers 112 and 114 include seats 139 and 140 for diaphragms 128 and 134, respectively, and diaphragm 128 includes a seat 142 for spring 130. Cover 114 includes a seat 144 (not visible in FIG. 2) for spring 136. When covers 112 and 114 are secured (e.g., sonic welded) to housing 102, covers 112 and 114 partially compress springs 130 and 136.

[0032]FIG. 3 is a cross-sectional view through pump 100 along line 3-3 shown in FIG. 1. Pump 100 includes first pumping chamber 132 and second pumping chamber 138. First pumping chamber 132 is in flow communication with a passage 146 through inlet nozzle 108 and inlet 104. Diaphragm 128 is located in first pumping chamber 132, and diaphragm 128 also is in flow communication with an air passage 148 through air nozzle 116. A support plate 150 is located between spring 130 and diaphragm 128.

[0033] Second pumping chamber 138 is inflow communication with a passage 152 through outlet nozzle 110 and outlet 106. Diaphragm 134 is located in second pumping chamber 138, and diaphragm 134 also is in flow communication with an air passage 154 through air nozzle 118. A support plate 156 is located between spring 136 and diaphragm 134. First pumping chamber 132 is in flow communication with second pumping chamber 138 via a check valve 158. Specifically, valve 158 is intermediate chamber 132 and chamber 138.

[0034] Check valves 124, 126, and 158 are well known. Generally, check valves 124, 126, and 158 each include a housing, a biasing spring, and a movable valve member having a sealing o-ring at one end. The movable valve member is normally biased to a closed position. Under the selected pressure conditions, the movable valve member moves from the closed position to an open position. Springs 130 and 136 and diaphragms 128 and 134 also are well known. The particular valves and springs selected depend, for example, upon the desired operation characteristics of pump 100. In pump 100, spring 130 is selected to be larger than spring 136 to provide the desired pump operation, as described below in more detail. Housing 102, covers 112 and 114, and nozzles 108 and 110 are molded using a plastic such as acetyl. Pump 100 also includes a plurality of o-rings 160, 162, 164, and 166 for preventing leakage.

[0035] Prior to operation, air lines are coupled to nozzles 116 and 118. Typically, the air lines extend from engine cylinders that operate 180 degrees out-of-phase so that alternating pressure and vacuum forces are applied to diaphragms 128 and 134. Rather than cylinders operating 180 degrees out-of-phase, it is possible to select cylinders having a different out-of-phase relationship, e.g., 120 degrees out-of-phase. In addition, a fuel line from a fuel tank is coupled to nozzle 108, and a fuel line to the cylinders is coupled to nozzle 110.

[0036] In operation, the engine cylinders generate positive and negative pressure pulses. For example, and in an engine with an even number of cylinders, when one cylinder is on an upstroke, there is at least one cylinder on a downstroke at the same time. Therefore, one cylinder pulse is positive and one cylinder pulse in negative. When the negative and positive pulses are exerted on opposite sides of a diaphragm, the pulses are additive. In fuel pump 100, when a positive pulse is present at nozzle 116 and a negative pulse is present at nozzle 118, fuel passes through valve 158 from first pumping chamber 132 to second pumping chamber 138. When the pulses are reversed, then a negative pulse is present at nozzle 116 and a positive pulse is present at nozzle 118. As a result, fuel is forced through outlet passage 152 and drawn into inlet passage 146.

[0037] In comparison to at least some known fuel pumps, and through use of the pump configuration and operation as described above, the pump inlet suction and outlet pressures are significantly increased. Such pressure increases enable use of one fuel pump even with an engine including multiple cylinder banks, and facilitates elimination of vapor and air bubbles in the fuel. Further, pump 100 does not include small, or narrow passages that are prone to be clogged by dirt or the like. Pump 100 also is compact. In addition, pump 100 can pump a significant volume of fuel, e.g., pump 100 may operate at one hundred cycles per second. In addition, leakback of fuel from the outlet fuel line is prevented by valve 126, which closes after fuel has been forced from outlet passage 152.

[0038]FIG. 4 is aside view of pump housing 102. As shown in FIG. 4, housing 102 includes an intermediate section 168 for housing valve 158. Section 168 is in flow communication with first and second pumping chambers 132 and 138.

[0039]FIG. 5 is a top view of pump housing 102. A passage 170 is in flow communication with pumping chamber 138 and outlet 106. FIG. 6 is a bottom view of pump housing 102. As shown in FIG. 6, a passage 172 is in flow communication with pumping chamber 132 and inlet 104.

[0040]FIG. 7 is an end view of a first end of pump housing 102. A first notch 174 in housing 102 is provided to accommodate nozzle 118. FIG. 8 is an end view of a second end of pump housing 102, and as shown in FIG. 8, a second notch 176 is provided to accommodate nozzle 116.

[0041]FIG. 9 is aside view of pump inlet cover 114, and FIG. 10 is a top view of cover 114. Cover 114 is identical to cover 112, and therefore, the following description with respect to cover 114 also describes cover 112. One advantage of having covers 112 and 114 identical is to ease assembly of pump 100. As explained above, cover 112 includes a nozzle 118.

[0042]FIG. 11 is a bottom view of pump inlet cover 114. FIGS. 12 and 13 are views of opposing ends of cover 114. As shown in FIG. 11, an air passage 178 extends from nozzle 118 so that air can flow through nozzle 118 against diaphragm 134. In addition, a seat 144 is provided for spring 136.

[0043]FIG. 14 is a side view, and FIGS. 15 and 16 are views of opposing end, of nozzle 108. Nozzle 108 is identical to nozzle 110, and therefore, the following description with respect to nozzle 108 also describes nozzle 110. One advantage of having nozzles 108 and 110 identical is to ease assembly of pump 100. Nozzle 108 is configured to be coupled to a fuel line, and to house a check valve as described above. In addition, nozzle 108 includes a groove 180 for receiving an oring to form a seal with housing 102. Nozzle 108 may, for example, be sonically welded to housing 102 during assembly of pump 100.

[0044]FIG. 17 is a top view of a pump 200 in accordance with a second embodiment of the present invention. Pump 200 includes a housing 202 which forms first and second pumping chambers 204 and 206. Housing 202 also includes inlet nozzles 208 and 210.

[0045] As best shown in FIG. 18, which is a cross sectional view of pump 200 along line 18-18 in FIG. 17, pump 200 includes a diaphragm 212 which extends through first and second pumping chambers 204 and 206. First and second check valves 214 and 216 are located in respective first and second chambers 204 and 206. Pump also including a fuel inlet 218 and a fuel outlet 220.

[0046] Housing 202 includes a main housing section 222, and first and second housing sections 224 and 226 which are sonically welded to section 222. Diaphragm 212 extends between first housing section 224 and main housing section 222, and a seal 228 extends between second housing section 226 and main housing section 222.

[0047] Prior to operation, air lines are coupled to nozzles 208 and 210. As with pump 100, and typically, the air lines extend from engine cylinders that operate 180 degrees out-of-phase so that alternating pressure and vacuum forces are applied to different sections of diaphragm 212. Rather than cylinders operating 180 degrees out-of-phase, it is possible to select cylinders having a different out-of-phase relationship, e.g., 120 degrees out-of-phase. In addition, a fuel line from a fuel tank is coupled to nozzle 218, and a fuel line to the cylinders is coupled to nozzle 220.

[0048] In operation, when a positive pulse is present at nozzle 208 and a negative pulse is present at nozzle 210, fuel passes through valve from first pumping chamber 204 to second pumping chamber 208. When the pulses are reversed, then a negative pulse is present at nozzle 208 and a positive pulse is present at nozzle 210. As a result, fuel is forced through outlet 220 and drawn into inlet 218.

[0049] From the preceding description of various embodiments of the present invention, it is evident that the objects of the invention are attained. Although the invention has been described and illustrated in detail, it is to be clearly understood that the same is intended by way of illustration and example only and is not to be taken by way of limitation. Accordingly, the spirit and scope of the invention are to be limited only by the terms of the appended claims. 

1. A fuel pump comprising: a pump housing comprising an inlet, a first pumping chamber in flow communication with said inlet, a second pumping chamber in flow communication with said first pumping chamber, and an outlet in flow communication with said second pumping chamber; a first nozzle comprising a check valve extending from at least one of said inlet and said outlet; and a valve intermediate said first pumping chamber and said second pumping chamber.
 2. A fuel pump in accordance with claim 1 further comprising a first diaphragm in said first pumping chamber.
 3. A fuel pump in accordance with claim 2 wherein said pump housing further comprises a first nozzle comprising an air passage extending therethrough, said air passage in flow communication with said first diaphragm.
 4. A fuel pump in accordance with claim 1 further comprising a second diaphragm in said second pumping chamber.
 5. A fuel pump in accordance with claim 4 wherein said pump housing further comprises a second nozzle comprising an air passage extending therethrough, said air passage in flow communication with said second diaphragm.
 6. A fuel pump in accordance with claim 4 further comprising at least one pump inlet cover enclosing one of said first and second diaphragms, and at least one bias member engaging and extending between said one of said first and second diaphragms and said pump inlet cover.
 7. A fuel pump in accordance with claim 1 further comprising a second check valve located in the other of said inlet and said outlet.
 8. A fuel pump in accordance with claim 1 further comprising a second nozzle extending from the other of said housing inlet and said housing outlet.
 9. A fuel pump in accordance with claim 8 further comprising a second check valve in said second nozzle.
 10. A fuel pump comprising: a pump housing comprising an inlet, a first pumping chamber in flow communication with said inlet, a second pumping chamber in flow communication with said first pumping chamber, and an outlet in flow-communication with said second pumping chamber; a first pump inlet cover secured to said pump housing and covering said first pumping chamber; a second pump inlet cover secured to said pump housing and covering said second pumping chamber; a first diaphragm in at least one of said first and second pumping chambers; and a bias member extending between one of said first and second pump inlet covers and said diaphragm.
 11. A fuel pump in accordance with claim 10 wherein said first pump inlet cover comprises a first nozzle and an air passage extending through said nozzle.
 12. A fuel pump in accordance with claim 10 wherein said second pump inlet cover comprises a second nozzle and an air passage extending through said nozzle.
 13. A fuel pump in accordance with claim 10 comprising a valve intermediate said first pumping chamber and said second pumping chamber.
 14. A fuel pump in accordance with claim 10 further comprising a second diaphragm in the other of said first and second pumping chambers.
 15. A fuel pump in accordance with claim 14 wherein said first pump inlet cover comprises a first nozzle and an air passage extending through said first nozzle, said air passage in flow communication with said first diaphragm.
 16. A fuel pump in accordance with claim 14 further comprising a second bias member extending between said second diaphragm and said pump housing.
 17. A fuel pump in accordance with claim 16 wherein said second pump inlet cover comprises a second nozzle and an air passage extending through said second nozzle, said air passage inflow communication with said second diaphragm.
 18. A fuel pump in accordance with claim 10 comprising a first check valve located in said inlet.
 19. A fuel pump in accordance with claim 10 comprising a second check valve located in said outlet.
 20. A fuel pump in accordance with claim 10 comprising an inlet nozzle extending from said housing inlet, and an outlet nozzle extending from said housing outlet.
 21. A fuel pump in accordance with claim 20 comprising a first check valve in said inlet nozzle and a second check valve in said outlet nozzle.
 22. A fluid actuated fuel pump assembly comprising; a body defining separate concave inlet and outlet hollows, a first pulse cover disposed over said inlet hollow, a first flexible diaphragm sandwiched between said first pulse cover and said body to define a first pulse chamber with said first pulse cover and a first pumping chamber with said inlet hollow, said body defining a fuel intake passage for admitting fuel into said first pumping chamber as said first diaphragm moves away from and toward said inlet hollow to vary the volume of said first pumping chamber, a second pulse cover disposed over said outlet hollow, a second flexible diaphragm sandwiched between said second pulse cover and said body to define a second pumping chamber with said outlet hollow and a second pulse chamber with said second pulse cover, said body defining a fuel outlet passage for conveying full from said second pumping chamber as said second diaphragm moves away from and toward said outlet hollow to vary the volume of said second pumping chamber, said first pulse cover including a first pressure inlet communicating with said first pulse chamber and adapted for connection to a first source of regularly cycling pressure pulses to move said first diaphragm, said second pulse cover including a second pressure inlet communicating with said second pulse chamber and adapted for connection to a source of regularly cycling pressure pulses to move said second diaphragm, a fuel transfer valve through which fuel is pumped from said first pumping chamber to said second pumping chamber in response to said first diaphragm being moved toward said inlet hollow, including first biasing means for biasing said first diaphragm in a direction away from said inlet hollow, and second biasing means for biasing said second diaphragm in a direction toward said outlet hollow, said first and second biasing means and said transfer valve being axially aligned.
 23. A fuel pump assembly as set forth in claim 22 including first biasing means for biasing said first diaphragm in a direction away from said inlet hollow, and second biasing means for biasing said second diaphragm in a direction toward said outlet hollow, the biasing force of said second biasing means being less than the biasing force of said first biasing means, said first and second biasing means and said transfer valve being axially aligned.
 24. A fuel pump assembly as set forth in claim 23 wherein said body defines a transfer passage extending between said inlet and outlet hollows and said transfer valve includes a first poppet disposed in said transfer passage.
 25. A fuel pump assembly as set forth in claim 24 wherein said transfer passage presents a spring shoulder and said first biasing means consists of a first coil spring seated on said spring shoulder and engaging said first diaphragm.
 26. A fuel pump assembly as set forth in claim 25 including a cage seated in said transfer passage and presenting a valve seat, said poppet movably disposed in said cage, said poppet having a valve head for sealing engagement with said valve seat and a stem slidably supported in said cage, a valve spring interacting between said stem and said cage for urging said valve head into sealing engagement with said valve seat.
 27. A fuel pump assembly as set forth in claim 26 wherein said transfer passage presents a cage shoulder and said cage presents a cage shoulder seated on said cage shoulder.
 28. A fuel pump assembly as set forth in claim 27 wherein said body consists of a plastic material and said cage consists of a metal.
 29. A fuel pump assembly as set forth in claim 25 wherein said second pulse cover includes a spring seat and said second biasing means consists of a second coil spring seated on said spring seat and engaging said second diaphragm.
 30. A fuel pump assembly as set forth in claim 29 wherein said first and second pulse covers are identical and interchangeable.
 31. A fuel pump assembly as set forth in claim 29 wherein said spring seat consists of an annular groove receiving said second coil spring.
 32. A fuel pump assembly as set forth in claim 24 wherein each of said covers includes a bead recess facing said body and each of said diaphragms and includes an integral bead disposed in said bead recess of the associated cover.
 33. A fuel pump assembly as set forth in claim 32 wherein said second biasing means consists of a second coil spring, a spring retainer plate disposed between each of said first and second springs and each of said diaphragms and, a button axially aligned with said first and second biasing means and said transfer valve and extending from opposite sides of each diaphragm and for engaging the associated pulse cover and for engaging the adjacent retainer plate.
 34. A fuel pump assembly as set forth in claim 24 wherein said inlet and outlet passages and said first pressure inlet and said second pressure inlet are all parallel to one another.
 35. A fuel pump assembly as set forth in claim 34 including an inlet fitting disposed in said inlet passage and an outlet fitting disposed in said outlet passage, an inlet check valve disposed in said inlet fitting and an outlet check valve disposed in said outlet fitting.
 36. A fuel pump assembly as set forth in claim 35 wherein said check valves are identical to one another with said inlet check valve disposed to allow fluid flow only into said first pressure chamber and with said outlet check valve disposed to allow fluid flow only out of said second pressure chamber.
 37. A fuel pump assembly as set forth in claim 36 wherein said body consists of a plastic material and said fittings and consist of a metal.
 38. A fuel pump assembly as set forth in claim 35 wherein each of said fittings and includes a large supporting portion supported by said body and a tubular portion extending therefrom for connection to a fluid line.
 39. A fluid actuated fuel pump assembly comprising; a body defining a spherical concave inlet hollow facing in one direction and a spherical concave outlet hollow facing in the opposite direction, a first pulse cover in seating engagement with said body about said inlet hollow and presenting spherical concave inlet depression over said inlet hollow, a first flexible diaphragm sandwiched between said first pulse cover and said body to define a first pulse chamber with said inlet depression of said inlet pulse cover and a first pumping chamber with said inlet hollow, body defining a fuel intake passage for admitting fuel into said first pumping chamber as said first diaphragm moves away from and toward said inlet hollow to vary the volume of said first pumping chamber, a second pulse cover in seating engagement with said body about said outlet hollow and presenting a spherical outlet depression over said outlet hollow, a second flexible diaphragm sandwiched between said second pulse cover and said body to define a second pumping chamber with said outlet hollow and a second pulse chamber with said outlet depression of said second pulse cover, said body defining a fuel outlet passage for conveying fuel from said second pumping chamber as said second diaphragm moves away from and toward said outlet hollow to vary the volume of said second pumping chamber, said first pulse cover including a first pressure inlet communicating with said first pulse chamber and adapted for connection to a first source of regularly cycling pressure pulses to move said first diaphragm, said second pulse cover including a second pressure inlet communicating with said second pulse chamber and adapted for connection to a source of regularly cycling pressure pulses to move said second diaphragm, a transfer passage extending between said inlet and outlet hollows, and a first poppet valve disposed in said transfer passage for allowing fuel flow from said first pumping chamber to said second pumping chamber in response to said first diaphragm being moved toward said bottom of said inlet hollow, said inlet and outlet passages and said first pressure inlet and said second pressure inlet are all parallel to one another and transverse to said transfer passage, said inlet and outlet passages extending in opposite directions, and said first pressure inlet and said second pressure inlet extend in opposite directions.
 40. A fuel pump assembly as set forth in claim 39 including an inlet fitting disposed in said inlet passage and an outlet fitting disposed in said outlet passage, an inlet check valve disposed in said inlet fitting for allowing flow only into said first pressure chamber and an outlet check valve disposed in said outlet fitting for allowing only flow out of said second pressure chamber, each of said fittings and including a large supporting portion supported by said body and a tubular portion extending therefrom for connection to a fluid line.
 41. A fluid actuated fuel pump assembly comprising; a first flexible diaphragm defining a first pulse chamber and a first pumping chamber, a fuel intake passage for admitting fuel into said first pumping chamber as said first diaphragm moves to vary the volume of said first pumping chamber, a second flexible diaphragm parallel to said first diaphragm and defining a second pumping chamber and a second pulse chamber, a fuel outlet passage for conveying fuel from said second pumping chamber as said second diaphragm moves to vary the volume of said second pumping chamber, first pressure inlet communicating with said first pulse chamber and adapted for connection to a first source of regularly cycling pressure pulses to move said first diaphragm, a fuel transfer valve through which fuel is pumped from said first pumping chamber to said second pumping chamber in response to said first diaphragm being moved, said assembly characterized by said transfer valve being disposed between and in alignment with the center of said pressure chambers. 